The thermoforming art is well developed and normally such machinery includes mold carrying platens driven cyclically in relative movement toward and away from each other between open and closed positions to thermoform plastic parts on a mass production basis. Various machines have been proposed to satisfy various of the requirements for efficient and reliable thermoforming machines, and among them are machines incorporating some of the features disclosed in the following U.S. Pat. Nos.:
U.S. Pat. Nos. 3,105,270; 3,726,458; 3,216,491; 3,876,488; 3,338,997; 4,354,816; 3,346,923; 4,368,024; 3,577,596; 3,890,308; 3,719,445; 4,158,539.
Improvements in such systems have been generally concerned with efforts to increase the productivity of such machinery and to operate it at ever-faster speeds to turn out products at an ever-increasing pace. Much of the machinery which is in use is of a relatively heavy and complex nature and a need has been identified for smaller thermoforming systems which are, for instance, capable of the "trim-in-place" processing of polypropylene and other thermoplastic materials. A thermoformer of this type may, for example, provide a maximum mold size of 20.times.13 inches with a 5 inch depth of draw. Such a machine will handle 22 inches.times.30 inch diameter rolls of material in thicknesses up to 2 mm., at operating speeds of as much as 40 strokes per minute.